Since we simulated this dataset, we know the true population standard deviation for the individual observations. here σ = 3 and you computed the theoretical standard deviation for the sample mean, σ ¯ x = σ √ n . assuming the population standard deviation is known, the confidence interval uses a z, i. e.,it is ¯ x ± e where e = z α 2 × σ √ n . recall that z α 2 is the z-score corresponding to the α 2 = 0.05 2 = 0.025 quantile on the standard normal distribution. question 6: for a 95% confidence interval, what is the margin of error e? round to three decimal places. e =